Using Matlab for 3D figure analysis

Ok, so I am a COMPLETE noob to matlab. For a project I need to input a image (it can be 2D) into the program. I have incision needles that cover an area of a 2cm circular diameter. Basically given the image, I need to calculate the coordinates in which the incisions will be made to cover the area of the image. Now there is a little more to it than I described, but its not really important.

All I need help with is not the algorithm because I already made it, but I need someone to reference me to a website or video that will teach me what I need to perform the functions. This may include how I can use images so that Matlab can analyze it and plot it on a coordinate system.